1. Field of the Invention
The present invention relates to a radiotelephone system, particularly in the form of a private branch exchange within and/or outside one or more buildings, comprising a plurality of mobile subscriber units, a plurality of transmitter/receiver units which can be coupled with the subscriber units by radio links, and a central unit co-operating with the transmitter/receiver units.
2. Description of the Prior Art
In such a radiotelephone system, which is disclosed in EP-A-225 607, the individual transmitter/receiver units are connected with the central unit of the private branch exchange via connecting lines, so that the individual subscriber units are suitable for mobile use but are tied to the predetermined coverage of the transmitter/receiver unit. Another disadvantage of this prior art radiotelephone system lies in the fact that an expensive cable system has to be installed to connect the individual transmitter/receiver units with the central unit. This expenditure is nearly equal to that required for conventional private branch exchanges which are connected with the subscriber units by subscriber lines.
From Br Telecom Technol J Vol 4 No. Oct. 4, 1986, "Controlled Radio Coverage in Buildings", D. A. Palmer et al, a radiotelephone system is known in which the transmitter/receiver units are provided, for example, on each floor of a building, and in which these transmitter/transceiver units are connected with the individual subscriber units via leaky feeders. This system suffers basically from the same drawbacks as those mentioned for the system referred to above since a fixed wiring system is required.